A Pilot Study of Rapid Haplotyping Procedure for Personalized Dosing of Dichloroacetate (DCA) in Healthy Volunteers

Overview

The purpose of this study is to identify and analyze the frequency of GSTZ1 haplotypes in a healthy adult population and determine the pharmacokinetics of Dichloroacetate (DCA) metabolism based on haplotype analysis. The DCA drug is the first targeted treatment for Pyruvate Dehydrogenase Complex Deficiency (PDCD). This pilot study, focuses on developing a high throughput, sensitive and accurate screening test for determining glutathione transferase zeta 1 (GSTZ1) haplotype status in individuals who would be treated with DCA.

Pyruvate dehydrogenase complex (PDC) deficiency (PDCD) is a rare disease of mitochondrial energy failure with the life of expectancy of affected children severely truncated. Treatment of PDCD remains a serious, unmet challenge. Dichloroacetate (DCA) represents the first targeted therapy for PDCD by stimulating residual PDC activity. Cumulative experience with DCA has revealed dose accumulation in a subset of the population. This can be abated through personalized dosing of DCA, assigned by haplotype variation in the gene encoding glutathione transferase zeta 1 (GSTZ1), which biotransforms DCA to glyoxylate. Haplotype variations in GSTZ1 influence the kinetics and dynamics of chronically administered DCA. A single dose of DCA has a bioavailability approaching unity and is widely distributed throughout the body. The plasma half-life (t ½) is \~1 hr in drug-naïve subjects. Gender does not influence DCA kinetics or metabolism. The major route of biotransformation is via dehalogenation to glyoxylate by glutathione transferase zeta 1 (GSTZ1). DCA is a mechanism-based inhibitor of GSTZ1, so repeated administration results in increased plasma t ½ and decreased clearance.

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